Researchers regularly sound sirens about the vulnerability of America's infrastructure to terrorist attacks, citing lack of security and incomplete or incoherent disaster preparedness plans. But our power grid, one of the country's most vital technological assets, may be safer than we think. Why? Because it's so screwed up.

The scariest reports about the fragility of our power grid focus on its interdependence. There have been cases in which a grid disruption in one location has led to failures in surprisingly faraway locations. (Science Daily recalls a blackout in 2003 that hopped from Ohio to NYC, then to Canada.) Hearing such a story emphasizes one aspect of the nation's power grid, and power grids in general: They are connected to one another at the speed of light, so disruptions are unpredictable, hard to get in front of and potentially problematic not just at their source, but almost anywhere.

Much has been written about this interconnectedness, and the grid's susceptibility to attack is generally described with so-called "Topographical" models, which emphasize the domino-like effect that has been observed during some outages. This is where doomsday terrorism scenarios come from.

A paper in the American Institute of Physics' Chaos journal comes bearing a different message: Calm down. Why? Because out grid is simply too disorganized and unpredictable to allow a small attack to grow large. Let's call it... security by absurdity.

Researchers from the University of Vermont and Penn State ran a simulation against data provided by the North American Electric Reliability Corporation, designed to match real world failures and their effects against what is predicted by both a topographic model, and a new model of their own making, which focuses on the basic physics of the transmission of electricity. (The paper can be purchased here, and is summarized here.)

The results suggest flaws in the topographic model, in no small part because the way neighboring power stations react to failures is wildly unpredictable. The tight, consistent and predictable interconnection between parts of the power grid required for a wide-scale disruption, or domino effect, just doesn't exist as some had assumed.

This, the researchers claim, is the result of years and years of piecemeal expansion of the power grid that lacked broad consistency and logic, bending to the needs of local and state power providers at a cost to uniformity. Researcher Paul Hines told Science Daily:

Our system is quite robust to small things failing -- which is very good. Even hurricanes have trouble taking out power systems. Hurricanes do cause power system failures, but they don't often take out the whole system.

Great news, right? It's a double-edged sword. Just as the unpredictability of the behavior of our power grid makes it difficult for those with malign ends to damage it, it makes large-scale overhaul extremely difficult. That the grid may confound would-be terrorists is at best an unintended evolutionary side-effect of this country's inconsistent process of modernization.